Development of a groundwater biobarrier for the removal of polycyclic aromatic hydrocarbons, BTEX, and heterocyclic hydrocarbons.
A full scale funnel-and-gate biobarrier has been developed for the removal of tar oil pollutants at an abandoned tar factory site near the city of Offenbach, Germany. Laboratory and on-site column studies were done to determine the operation parameters for microbiological clean-up of the groundwater polluted with 12,000 microg/L mono- aromatic hydrocarbons such as benzene and the xylenes, 4,800 microg/L polycyclic aromatic hydrocarbons such as naphthalene and acenaphthene, and 4,700 microg/L heterocyclic aromatic hydrocarbons such as benzofuran and benzothiophene. In the laboratory study, a residence time of approx. 70 h proved to be sufficient for aerobic pollutant biodegradation. Up to 180 mg/L H(2)O(2) were added and did not lead to any toxic effects to the degrading bacteria. The feasibility of the concept was confirmed in an on-site pilot study performed with a sedimentation tank (removal of ferric iron) and two bioreactors. In the bioreactors, >99.3% of the pollutants were degraded. Biodegradation activity corresponded to a significant increase in numbers of pollutant degrading bacteria. In the bioreactors, a fast dissociation of H(2)O(2) was observed resulting in losses of oxygen and temporary gas clogging. Therefore, a repeated addition of moderate concentrations of H(2)O(2) proved to be more favourable than the addition of high concentrations at a single dosing port. The full scale biobarrier consists of three separated bioreactors thus enabling extended control and access to the reactors. The operation of the funnel-and-gate biobarrier started in April 2007, and represents the first biological permeable reactive barrier with extended control (EC-PRB) in Germany.
Tiehm
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Department of Environmental Biotechnology, Water Technology Center, Karlsruher Str. 84, Karlsruhe 76139, Germany. tiehm@tzw.de
Müller
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Alt
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Jacob
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Schad
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Weingran
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D001554:Benzene / Q000302:isolation & purification / Q000378:metabolism; D001555:Benzene Derivatives / Q000302:isolation & purification / Q000378:metabolism; D001673:Biodegradation, Environmental; D019149:Bioreactors; D005843:Geography; D005858:Germany; D006571:Heterocyclic Compounds / Q000302:isolation & purification* / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000378:metabolism; D011084:Polycyclic Aromatic Hydrocarbons / Q000302:isolation & purification* / Q000378:metabolism; D014050:Toluene / Q000302:isolation & purification / Q000378:metabolism; D014871:Water Microbiology; D014874:Water Pollutants, Chemical / Q000302:isolation & purification / Q000378:metabolism; D018508:Water Purification / Q000379:methods; D014881:Water Supply / Q000032:analysis*; D014992:Xylenes / Q000302:isolation & purification / Q000378:metabolism
D001555:Benzene Derivatives; D006571:Heterocyclic Compounds; D011084:Polycyclic Aromatic Hydrocarbons; D014874:Water Pollutants, Chemical; D014992:Xylenes; D014050:Toluene; D006861:Hydrogen Peroxide; D001554:Benzene; C004912:ethylbenzene